/*
* Created on 15-Mar-2006
* Created by Paul Gardner
* Copyright (C) 2006 Aelitis, All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* AELITIS, SAS au capital de 46,603.30 euros
* 8 Allee Lenotre, La Grille Royale, 78600 Le Mesnil le Roi, France.
*
*/
package com.aelitis.azureus.core.util;
import java.util.*;
public class
CopyOnWriteList
{
private volatile List list = new ArrayList();
//private volatile int version;
public void
add(
Object obj )
{
synchronized( list ){
List new_list = new ArrayList( list );
new_list.add( obj );
list = new_list;
//version++;
}
}
public boolean
remove(
Object obj )
{
synchronized( list ){
List new_list = new ArrayList( list );
boolean result = new_list.remove( obj );
list = new_list;
//version++;
return( result );
}
}
public void
clear()
{
synchronized( list ){
list = new ArrayList();
//version++;
}
}
public boolean
contains(
Object obj )
{
return( list.contains( obj ));
}
public Iterator
iterator()
{
return( new CopyOnWriteListIterator( list.iterator()));
}
public List
getList()
{
// TODO: we need to either make this a read-only-list or obey the copy-on-write semantics correctly...
return( list );
}
public int
size()
{
return( list.size());
}
/*
public int
getVersion()
{
return( version );
}
*/
private class
CopyOnWriteListIterator
implements Iterator
{
private Iterator it;
private Object last;
protected
CopyOnWriteListIterator(
Iterator _it )
{
it = _it;
}
public boolean
hasNext()
{
return( it.hasNext());
}
public Object
next()
{
last = it.next();
return( last );
}
public void
remove()
{
// don't actually remove it from the iterator. can't go backwards with this iterator so this is
// not a problem
if ( last == null ){
throw( new IllegalStateException( "next has not been called!" ));
}
CopyOnWriteList.this.remove( last );
}
}
}
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